I've been searching the web for info regarding companions and what effects their missions and subsequent results. Unfortunately I haven't been able to find any decent sources for how, what and why stuff happens - atm, I'm just clicking buttons and sending them off on missions as much as possible. So obviously I have a few questions regarding this, and I'm kinda hoping we can gather all the "good stuff" about companions and how to maximize the crew skills.

!I'm not talking about what skills go well together - that info is fairly easy to find (i.e. Synth, Archeology and Underworld goes nicely together etc..).

Missions: What effects them?

Some places I've read that a companions stats influence missions (stacking crit on gear = higher chance of criting a mission).

I've read that affection effects both time and outcome (not just failure/succes, but also actual rewards - higher chance of crit etc).

Bonus skill (like a companion with +X to a skill). Haven't found much on this (I'm guessing it will change success/failure-rate), but will it also change time and/or rewards?

--Disclaimer: I'm pretty sure that not all of which I've written above is correct - just stating what I've read on various sites, to clarify why I'm "slightly" confused...

How to level affection cheapest? Affection is clearly not a bad thing, so...

Yes, I know that doing missions and choosing the proper answers/actions is the cheapest, but how can I speed it up the best way?
- So far I've thought of buying all the proper gifts for the companion and considering the fact that it gets more expensive the higher your affection-level is, it might be a good idea to start this ASAP while leveling. Especially considering three things:
a) Your char recieves a 30s debuff, preventing you from spamming gifts(You get the debuff, not the companion - so you can't cycle through companions and give them each a gift),
b) if you gain the affection earlier your companion will perform better in fights and
c) your quest-affection will count towards the higher levels.

I currently have Level2 affection with my first companion, and here's some numbers for the gifts I've bought so far. Obviously I've bought the "Loved"-category - aka the gifts that should improve affection most.
Rank 1: Price 200 and Affection-gain 27
Rank 2: Price 600 and Affection-gain 54

I was kinda surprised about this, since I had assumed that Rank 2 gift would be better, especially considering my companion has Rank 2 Affection. However these numbers have made me buy a lot of Rank 1, which I use as often as possible while questing.

So come on - share your epic knowledge of this little bit of SW:TOR

TLR: Too short, didn't write...